Patent GB-283105-A (GB)
Title: Improvements in the manufacture and production of hydrocarbons poor in hydrogen
IPC: C07C5/44
Filed: 1927-12-12
Abstract: 283,105. I. G. Farbenindustrie Akt.- Ges. Jan. 3, 1927, [Convention date]. Motor spirit.-Hydrocarbons poorer in hydrogen than the. initial material are produced by carrying out a catalytic dehydrogenation in the presence of chlorine, if desired with the addition of other gases or vapours, at ordinary or reduced pressure. The process is described as an improvement in the last stage of the processes described in Specifications 261,393 and 293,887, [both in Class 1 (i), Chemical processes &c.], in which a lower olefine is treated to obtain liquid polymerization products which are then subjected to catalytic dehydrogenation. In the dehydrogenation process, rise of temperature may be avoided by admitting the chlorine in small portions or by diluting it with nitrogen, carbon dioxide, steam, &c., and the catalysts mentioned are active carbon, silica, pumice, zinc borate, vanadiferous catalysts, aluminium phosphate, chromium oxide, and copper chloride. The reaction may be facilitated by means of actinic ravs from a mercury lamp or by silent electric discharges, and the hydrochloric acid produced may be employed in cracking hydrocarbons in presence of catalysts, especially activated aluminium, iron. and the like, which may be obtained by etching the surface of the metals with acids or metal salt solutions. The dehydrogenation process may be applied to hydrogenation and cracking products, mineral oils, tars. extraction products from coal and the like, or fractions of the same. Preferably such materials are first distilled to eliminate ash and, if desired, less suitable fractions. The hydrogenation is usually accompanied by a more or less extensive cracking into smaller molecules. Any gaseous products may be recovered by cooling or adsorption in active carbon or the like. All substances which favour the production of methane or the deposition of carbon should be excluded from the reaction chamber. The products may be treated to separate the olefines which may be converted into alcohols, and the di-olefines which may be used] for the production of synthetic rubber. The products may be added to liquid fuels to prevent knocking, or may be subjected to a catalytic process for example at 500-600‹ C. with or without pressure and if desired in the presence of other gases such as nitrogen or carbon dioxide to convert them into aromatic hydrocarbons. In an example, mineral oil of boiling point 250- 400‹ C. is passed at 350‹ C. together with a mixture of chlorine and nitrogen over active charcoal or active silica. About 30 per cent of the product boils below 200‹ C., about half of which consists of unsaturated substances while 40 per cent boils between 200 and 250‹ C. and is unsaturated to about 40-50 per cent. The Specification as open to inspection under Sect. 91 (3) (a) states that when activated metals are employed, the dehydrogenation and cracking may be effected together, and contains an example in which melted paraffin is allowed to flow over active carbon at 400‹ C., a current of chlorine being passed over at the same time, and 90 per cent is converted into a liquid product of which 40 per cent boils below 200‹ C. of which fraction nearly half is olefines. The amount of the unsaturated hydrocarbons can be increased by again passing the liquid products with more chlorine through the reaction chamber. Some gaseous olefines and paraffins are produced, but the quantity may be reduced by working at lower temperatures and diluting the chlorine with nitrogen. This subject-matter does not appear in the Specification as accepted.